Add weapon dmg - how?

[Marinchev]

Hey guys - I was wondering how to add a percentage of the player's total HP as damage to an enchant for a weapon? I tried with actorvalue through the perk system from the CK, BUT... it doesnt add a percent from the total Hp, it adds percent from the current Hp in realtime - for example, if I take damage, the added value gets smaller with the amount of damage I take. I want it to be a static value from my total HP, not a realtime value from the HP I have left from a fight. I hope I made that clear enough, English isnt very native to me. 

 

So I'm guessing I need a script for that, question is what function do I use? Im not that familiar with papyrus scripts? Thanks in advance!